Add HasSubclasses function to class hierarchy analysis.

runtime/vm/class_table.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_CLASS_TABLE_H_
 #define VM_CLASS_TABLE_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/globals.h"
@@ skipping 20 matching lines @@
   intptr_t IsValidIndex(intptr_t index) const {
     return (index > 0) && (index < top_);
   }
 
   void Register(const Class& cls);
 
   void VisitObjectPointers(ObjectPointerVisitor* visitor);
 
   void Print();
 
+  // Returns true if the class given by its cid has subclasses.
+  // Must not be called for kDartObjectCid.
+  bool HasSubclasses(intptr_t cid) const;
+
   // Returns an array containing the cids of the direct and indirect subclasses
   // of the class given by its cid.
   // Must not be called for kDartObjectCid.
   ZoneGrowableArray<intptr_t>* GetSubclassIdsOf(intptr_t cid) const;
 
   // Returns an array containing instance functions of the given name and
   // belonging to the classes given by their cids.
   // Cids must not contain kDartObjectCid.
   ZoneGrowableArray<Function*>* GetNamedInstanceFunctionsOf(
       const ZoneGrowableArray<intptr_t>& cids,
@@ skipping 15 matching lines @@
   intptr_t capacity_;
 
   RawClass** table_;
 
   DISALLOW_COPY_AND_ASSIGN(ClassTable);
 };
 
 }  // namespace dart
 
 #endif  // VM_CLASS_TABLE_H_